The Labour Party leader, Phil Goff, says claims that Chris Carter discussed a leadership coup with fellow MPs, are totally untrue.
Following a six-hour meeting in Wellington, Labour's ruling council decided to expel Mr Carter from the party on Monday night, saying he had bought the party into disrepute.
The Te Atatu MP was kicked out of the party's Caucus in July after he circulated an anonymous letter to reporters which aimed to undermine the leadership of Phil Goff.
Labour Party president Andrew Little has confirmed that Mr Carter claimed in his submission to the council he met with three other Labour MPs the night before the letter was sent, and discussed when a leadership challenge should take place.
He also claimed that 17 of the party's 43 MPs would vote against Mr Goff.
Mr Goff says it's totally untrue and has challenged Mr Carter to name names. He says he had the unanimous support of Labour MPs to sack the MP from the caucus.
Mr Carter does not think he got a fair hearing, and says the decision to expel him from the party is a ridiculous over-reaction.
But Mr Goff says Mr Carter has to be accountable for his actions and it is time to move on.
"It's now been dealt with and we're past it. Chris Carter no longer has relevance to the Labour Party - he's not a member of the party and it's been months since he's been a member of the Caucus."
Mr Carter says he is appalled by the way Labour Party bosses have behaved over his expulsion.
The independent MP says he only learned of his expulsion when he heard it on the radio.
Mr Carter attended the meeting on Monday but left by a back door, avoiding media, about two hours before the ruling council announced its decision.
However, he says he would have expected the party to have texted or left a voice message advising him of its decision.
"I think I've been treated appallingly. I think it's been petty, spiteful and an over-reaction and all designed to lift a failing leader.
Mr Carter says he will decide in the next week whether he will appeal against the decision.
Decision not taken lightly - president
Labour Party president Andrew Little says the decision to expel Mr Carter was not taken lightly and the council was careful about the way it conducted the meeting.
Mr Little says Mr Carter's actions were deceptive and clearly calculated to cause damage to the Caucus and Labour's reputation, and at no time has he accepted the gravity of his actions or shown any contrition.
Mr Little told Morning Report that Mr Carter spoke at length on Monday night.
"His big concern was that he felt that in the last few months he felt unsupported by the leadership, and it was presented as some sort of justification or explanation for his actions.
"But when the gravity of what he'd done was put to him, there was a sense that he didn't regard it as that grave, or that significant."
Mr Little says the decision to expel Mr Carter was not unanimous, but was supported by an overwhelming majority.
Expulsion from a party is usually permanent, however, a future council of the Labour Party could consider re-admitting Mr Carter, he says.